The projects in this program are concerned with the investigation of a number of vasoactive hormones as possible mediators or modulators of pulmonary vascular diseases. These hormones include: vasoactive intestinal peptide (VIP), two novel vasoactive lung peptides, prostaglandins and related lipids, and angiotensin converting enzyme. The experimental models under study include: pulmonary thromboembolism, alveolar hypoxia, pulmonary edema, "respiratory distress syndrome", and shock lung. Pulmonary arterial, aortic blood, pulmonary lymph, and pulmonary endothelial cells are analyzed. Whenever possible, samples from human subjects with these disorders also will be examined.